Alarm cable and switch



June 11, 1940. c. M. sLAcK Er-AL 2,204,237

ALARK CABLE `Am) SWITCH Filed Aug. 2o, '193e l /9 "5 za Passwd .lm mfrgi 1, i940 UNITED STATES amsn 'Aman om' `.arm swrrcn Charles M. Slack, Glen-RidgaamlGeorge G. Uromartie, Maplewood, N. J.

Application Annet zo, lass, serial No. 225.8253v nomme.

This invention relates to alarms and alarm cables. More particularly the invention is directed to alarm cables characterized by a novel arrangement of its conducting wires and switches as well as to novel switches for use with an annunciator forinitiating an alarm when the temperature of the ambient exceeds a predetermined critical temperature. More specifically the invention provides a novel and unique combination of conductors and switches which may be readily reeled because the flexibility of the conductors is not seriously impaired, which may be transported without anyi` great danger of the separation of the switches from the conductors, which may be easily secured to a support, such as, a wall or ceiling, and will be inconspicuous and its switches may be easily tested. Still another aspect of the invention is the provision of a switch which is relatively simple and inexpensive to manufacture and may be easily combined with the conductors. Other aspects of the invention will be readilyl apparent from the following description and drawing, wherein,

Figure 1 represents an alarm circuit embodying the invention.

Figure 2-represents a side view of the novel switch.

Figure 3 is a perspective view of a length of the cable per se. f

Figure 4 represents a sectional view of the combined switch and cable. f

Figure 5 is a cross-sectional view taken on line 5--5 of Figure 4. Figure 6 is a perspective view of the element 3;, which is adapted to spring to position and complete the circuit between the two contacts of the switch when the fusible element thereof has been deformed.

As shown in the drawing the cable I comprises 0 a pair of flexible conductors III and II, and each conductor may consist of a large number of fine strands of copper wire. Enclosing eachof said conductors along the length thereof is a flexible insulator I3 which maybe composed of soft rub- 45 ber or the like. The insulators are secured to Aeach otheralong their lengths ,as shown by an appropriate adhesive or by any other desirable means to provide a unitary cable comprising a pair of conductors maintained in position with respect to each other and insulated from each other.

In accordance with this invention, novel l switches, such as thermally responsive switches, are combined with the cable to provide a prefabu ricated alarm cable. The cable may be of any (ci. zoo-14:)

vlength and combined therewith along spaced intervals of four or iive feet arev the novel switches which may be readily mounted and demounted and replaced if required and which do not seriously impair the flexibility of the cable as a whole.

Each switch may comprise upper and lower elements 'Il and I5, and these elements are exactly alike in all details so that it is necessary to provide but one set of tools and to make only l0 one type of element in manufacture. Each element may comprise a rigid ilat and narrow strip Il of highly conducting metal vwhich may be relatively thin and has a high melting point. The width of each strip I6 is not materially 15 greater than the diameter of insulator I3 and is preferably less than-.said dimensin. Integral "with each strip Ii'at each end thereof is an outwardly extending half diamond retaining and connecting thin contact I1.

y The retaining contacts il are so disposed relative to the strip I8 that their bases extend along the length of strip I6; and the altitude or length `of each contact I'I is greater than the thickness of the annular insulator I3, but less than the g5 outside diameter of insulator I3 so that when the retaining contacts are inserted through the rubber insulator they will extend through a portionr thereof and between the strands of the conductors and into the other part of the insulator, but so will not extend through the outer part of the insulator and at the same time will not cause any great distortion of th conductors and will be maintained in position by both the strands of the conductor and the insulatorsurrounding the same. If desired the length of the connectors Il may be such that they extend entirely through the insulators and may be crimped over at the outside thereof. StripV I8 has a pair of square openings I8 therein located between the retainers 0 I1. Each opening Il is located near the retainer I1. And between said openings Il, and. located closer to one of them is a pair of supports I9 struck out of the outer marginal portions of the strip I6. The free ends thereof are located away from the under face of the strip I8.

In order to assemble the elements Il and I5 a pair of similar cross insulators 2U are employed. First, elements Il and I5 may be arranged one so above the other, with the retaining tapered pins I1 extending-away from eachother and with the struck out portions I9 located at opposite ends thereof. y A cross insulating spacer 20 has one portion thereof located in each of the openings Il of the lower element Il and is peened over to secure the same thereto.

Then a resilient spring member shown in Figure 6 and having a square opening 2| at one end and a resilient tongue 22 is mounted on one of the projections of the cross and the tongue portion 22 thereof extends downwardly to the lower element il and presses thereagainst.

The upper element Il is mounted on the projection of the crosses 20 and these projections are peened over to lock the members I4 and I5 to each other in the form of a rigid and rugged structure. The end of tongue 22 is raised upwardly between the struck out parts I9 and a fusible band or short strip 23 of a low melting point metal, such as Woods metal, is bridged across the struck out portions i9 and retains the tongue 22 away from and out of contact with the lower element i5. The readily fusible metallic alloy strip 23 may be composed of Woods metal and may' extend straight across and bridge the struck outs I9 or they may be in the general form of a U and makes a frictlonal contact with the inner and outer edges of the struck out portions I8 and element il respectively to hold the strip 23 and tongue 22 in position and against displacement.

The cable hereiribefore described may be used and may he purchased in the open market. When this cable is employed, the insulators i3 are separated from each other at spaced intervals of one, two, three'or more feet depending on the desired number o1' switches per particular length of cable. The length of each separation is just slightly greater than the length of each switch so that the cable per se may aid in maintaining the switches in position. The switches are then in- Ser'ted and centrally located in these openings or separations located at spaced intervals along the length of the cable.

The retaining half diamond contacts or connectors il are embedded into the upper and lower insulated conductors as shown in Figure 4, with the strips i bearing snugly against the insulators i3 and the contacts Il extending through the thickness ci.' each insulator, between the strands of the conductors i0 and Il and up into the outer thickness of the insulators i3, but within the outer extremity thereof. The strands of the conductors which are slightly distcnded also act to hold the switch in position.

The side edges of the switches are located inside of the outer limits of the insulators I3 as shown in Figure 5. And, the depthwise dimension of each switch is small and preferably less than the outside diameter of insulators I 3 so that the cable per se is not seriously deformed.

It is also within the purview of this invention to clamp those portions of the insulators adjacent the ends of the separations and for this purpose there may be employed a wire clamp, or a nonconducting wrapping clamp is desired. In order that no dust or other extraneous matter which might accidentally cause a shortening of the elements i4 and I5 may be eliminated, there may be provided a non-conducting covering 26 of rubber or the like over the entire outside of that portion of the combined cable and switch sections. And, instead of using a spring and fusible elements as parts of the switch a bi-metallic thermostat structure may be employed.

In practice a length of this cable with the switches spaced along intervals thereof, is secured to the molding along the walls of, the room, so that in a normal sized room there are a number of these switches4 lnconspicously located at different places. The conductors are in series with a source of energy 21 and an annunciator, such as a bell 2l, and the switches are in parallel with said conductors. In the event of a flre, only one of the fusible retaining strips 2l need fuse to release the spring tongue 22 which will snap over to bridge elements Il and Iland complete the circuit so that the bell will beenergized, and sound an alarm.

Although the invention has been described in detail, it is not to be limited thereby because it is subject to modifications within its scope.

We claim:

1. The combination of a pair of elongated conductors, each of said conductors including a plurallty of conducting strands, electrical insulating means for said conductors, said insulating means located in close proximity to each other at places along the length thereof, a plurality of thermally responsive switching means spaced from each other at intervals along the length of said conductors, the major portion of said switching means located between said insulating means and disposed lengthwise along the length of said insulating means, said insulating means being in close proximity to said switching means along the length of said switching means and means axtending through said insulators and 'electrically connecting said conductors and said switching means, a portion of said last mentioned means located between a plurality of sald'strands of one of said conductors.

2. The combination of a pair of elongated conductors, electrical insulating means for said conductors, said insulating means located in close proximity to each other at places along the length thereof, a plurality of thermally responsive switching means spaced from each other at intervals along the length of said conductors and located between said conductors, said switching means disposed lengthwise along the length of said conductors and electrically connected to said conductors, the depth of said switching means between said conductors being not materially greater than the outside dimension of said insulating means, said insulators located closely adjacent said switching means along the length of said switching means and means cooperating with said insulating means to enclose substantially said switching means.

3. A prefabricated alarm cable comprising a plurality of conductors, insulating means therefor, said insulating means being in close proximity to each other at places along the length thereof, each of said conductors comprising a plurality of conducting strands, a plurality of thermally responsive switches spaced from each other along the length of said conductors and disposed lengthwise along the length of said conductors and being in close proximity to said insulating means along the length thereof and means electrically connecting said switches and said conductors, parts of said last means located between strands of said conductors.

4. A prefabricated alarm cable comprising a plurality of conductors, insulating means therefor, said insulating means being in close proximity to each other at places along the length thereof, a plurality of thermally responsive switches spaced from each other along the length of seid conductors and between said conductors, the width and depth of said switches being not materially greater than the greatest cross sectional dimencion of said insulating means. said switches disposed ylengthwise along the length of said insulating means and means secured to said switches and electrically connecting said switches to said conductors, said means puncturing said insulating means and contacting said conductors.

5. A prefabricated alarm cable comprising a pair of elongated conductors, each of said conductors comprising a plurality of conducting strands located close to each other, electrical lnsulating means surrounding each of said conduotors and located in close proximity to each other at places along the lengths thereof, thermally responsive switches spaced from each other along the length of said insulating means, the major portion of said switches located between said insulating means and means extending through said insulating means and between strands of said conductors for electrically connecting said switches and said conductors, said switches disposed lengthwise, along the length of said conductors and being in close proximity to said insulators along the length thereof, the over all cross sectional area of each of said switches being not materially greater than the said strands to maintain said switches in place cross sectional area of the combined insulators.

6. A prefabricated alarm cable comprising a pair of conductors, each of said conductors comprising -a plurality of conducting strands, insulating means surrounding each of said conductors and maintained in close proximity to each other over the major portion of the length of said cable, a plurality of thermally responsive switches spaced from each other and located in openings between said insulating means, and means electrically connecting said switches and said conductors, said-means extending through said insulating means and between said strands, the major portion of said switches located between said insulating means, said switches disposed lengthwise along the length of said insulating means and being in close proximity thereto'along the length thereof, the breadth and depth of each of said switches being not materially greaterthan the greater dimension of the over all cross sectional area of the combined insulators.

'7. A prefabricated alarm cable comprising a I pair of elongated conductors, elongated insulators surrounding said conductors and maintained in close proximity to each other along a major portion of their length, a plurality of thermallylresponsive switches including electrical connectors extending through said insulators and contiguous with said conductors, said switches disposed lengthwise along the length of said insulators and located between said insulators at spaced intervals along their` length, the majorv portion of said' switches located between said conductors, said switches adapted to be maintained in place solely by the connectors thereof extending through said insulato's and contacting said conductors.

8. A prefabricated .-.larm cable comprising a pair of elongated conductors, elongated insulators surrounding said conductors and maintained in close proximity to each other along the maior portion of their length, each oi' said conductors' including a plurality of elongated conducting strands, a plurality of thermally responsive switches spaced from each other and the major part thereof located in spaced openings between said insulators, said switches including means extending` through said insulators and between and to electrically connect said switches and said conductors. y

and another contact of each of said switches extending lengthwise along the length of said insulators and being in close proximity to the other of said insulators and electrically connected to the other of said conductors, insulating means insulating said contacts from each other, a spring element for bridging said contacts, one end of said element connected to one of said contacts and a fusible means for maintaining its other end away from the other contact, the width of said switches being not materially greater than the width of 'said insulators.

10. A switch comprising'a pair of narrow strips of conducting material, an insulator located at each end thereof for insulating said strips from and mechanically connecting said strips to each other, a resilient tongue for electrically connecting said strips, one end of said tongue connected `to one of said strips and fusible means for maintaining the free end thereof from the other strip whereby when said means fuses the free end of said tongue will move to said other strip to electrically connect said strips, the distance between said strips being not materially greater than the width of said strips.

11. A switch comprising a pair of narrow conducting strips having openings in the ends thereof, a resilient conducting tongue located between said strips and having an opening in one end thereof, an insulator extending through the opening in said tongue and the openingsl in one end of said strips, an insulator extending through the openings in the other end of said strips, said strips connected to and spaced from each other by said insulators, a fusible member for maintaining the free end of said tongue from one of said strips.

12. A prefabricated alarm cable comprising a plurality of conductors, insulating means therefor, each of said conductors comprising a plurality of' conducting strands, said insulating means being parallel, superimposed one on the other andsecured together along the adjacent faces thereof, said insulating means being unsecured to each other at relatively short lengths at relatively long length intervals along the length thereof, a plurality of thermally responsive switches located between said unsecured short lengths of said insulating means, the width of said switches being not materially greater than the diameter of said insulating means, the opposing faces of said unsecured short lengths of said insulating means being closely adjacent the perimeter of said switches, and means electrically connecting said switches and said conductors, said means embedded in said insulating means and located between strands of said conductors.

13. A prefabricated alarm cable comprising l.

plurality of conductors, insulating means therefor, each of said conductors comprising a plurality of conducting strands, said insulating means being parallel and superimposed on each other and secured together along adjacent faces thereof, said insulating means being separated from each other in relatively short lengths at relatively long intervals along the length thereof, a plurality of relatively narrow switches located between said separated short lengths of said insulating means, the opposing faces of said separated short lengths of said insulating means being closely adjacent the perimeter of said switches, means electrically connecting said switches and said conductors, said means embedded in said insulating means and located between strands of said conductors, means cooperating with said insulating means for substan tially enclosing said switches.

14. A switch comprising a pair of narrow con-V ducting strips having openings in the ends there- CHARLES M. SLACK. GEORGE G. CROMARTIE. 

